In the past decades a lot of research has been directed to fetal monitoring transducers and devices. These devices are used to either record the fetal heart beat and the uterine contractions during pregnancy and birth or to create images of the fetus in the womb. For the latter one obstetric ultrasonography is usually performed, wherein sonography is used to visualize the embryo or fetus in its mother's uterus (womb). This procedure is a standard part of prenatal care, as it provides a variety of information regarding the health of the mother and the fetus, the progress of the pregnancy, and further information on the baby before and during birth.
In order to record the uterine contractions during pregnancy and birth slightly different machines are used. The machines used to perform such monitoring are called cardiotocographs, more commonly known as electronic fetal monitors (EFM).
In both above-mentioned fetal monitoring devices one or more ultrasonic transducers or other ultrasonic-based sensors are used. These ultrasonic transducers and other electronic periphery devices need to be encapsulated in a liquid-tight housing. Usually two half-shells are used to provide an encapsulated volume for the measurement transducers and the peripheral devices of the fetal monitoring apparatus.
One issue that commonly appears is the serviceability of the transducers and the peripheral devices. After usage the transducer housings have to be cleaned and disinfected. On the other hand, the transducer housing needs to be absolutely liquid-tight, as the housing is usually contaminated with a lot of blood and mucus if used during birth. In most cases the two half-shells of the transducer housing are therefore either glued together or joined with each other using screws.
In case the two half-shells of the transducer housing are glued together this has a main (negative) impact on the serviceability of the transducer housing. In case the two housing parts are glued together, it is hard to open the transducer housing in order to repair or replace any part inside the housing, since the glue bond in this case needs to be released. Releasing the glue bond might be difficult and could also destroy parts of the housing.
A connection of the two half-shells of the transducer housing via screws is also not advantageous. First of all, screws have a negative visual impact on the transducer housing and could negatively influence the design of the transducer housing. Further, the metal parts of the screws could have a negative influence to a radio system of a wireless transducer. Even further, the screws occupy space within the transducer housing. Apart from that gaps and sharp edges might occur when using screws as connection parts, which could lead to unwanted injuries of the patient. Another negative effect is that a physician him/herself could try to open the transducer housing in order to repair or clean the ultrasonic transducer or peripheral devices connected thereto. However, such a self-repair shall be prevented in any case.
There are strong regulations in the medical field that stipulate that a medical device may not be opened by any unauthorized person, but only by authorized persons that are in possession of a special opening tool.